Method of filling flashbulbs



Oct. 16, 1962 s. R. BENNETT ETAL 3,058,499

METHOD OF FILLING FLASHBULBS Original Filed Oct. 26, 1950 In E SEDGWIC K RBENNETT ALLEN MERTZ INVENTORS BY 22 S ATTORNEY United States Patent 3,058,499 METHOD OF FILLING FLASHBULBS Sedgwick R. Bennett and Allen Mertz, Williamsport, Pa, assignors, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, Del., a corporation of Delaware Original application Oct. 26, 1950, Ser. No. 192,224, now Patent No. 2,772,703, dated Dec. 4, 1256. Divided and this application Dec. 3, 1956, Ser. No. 625,697 1 Claim. (Qt. 141-9) This invention relates to a method and apparatus for introducing filamentary material into a container. More particularly, it relates to a method and apparatus for introducing and distributing a metallic filamentary material such as shredded foil into flashlamp envelopes.

The method of introducing and distributing either long single strands of wire or short lengths of shredded foil into flashlamps aided by a moving current of air is well known to the art, and has been described, for example, in Korver Patent Number 2,115,423 and Geiger and Davidson Patent Number 2,347,046. In accordance with the Korver patent the wire is sucked into a tube by means of a vacuum created with a venturi and then propelled through a tube by the current of air passing therethrough whereupon the wire is distributed in the bulb area of the flashlamp by recur-rent air flow. In the Geiger and Davidson patent a suction means is used on the far side of the flashlamp. However, the results are quite similar in that the shredded foil is sucked into a tube and carried therein into the flashlamp where the shreds are distributed by the recurrent flow of air as the air leaves the vessel and proceeds to the point of suction leaving the shredded particles distributed in the flashlamp envelope. Although the methods shown and described in the above noted patents have given reasonably acceptable results with single strand wire or with fills made of a single size shredded filament, considerable difiiculty has been encountered in the art when attempts were made to use these processes in the manufacture of a focal plane type of flashlamp. These focal plane lamps are made with the use of two difierent gauges of materials wherein the cross section of one is much coarser than the cross section of the other. The fills are introduced separately in such a manner that the coarse fill occupies the upper part of the bulbous portion of the bulb, and the fine fill occupies the space immediately beneath, and surrounds or is adjacent to the igniting means. When attempts were made to make this type of lamp with the filling devices of the prior art it was virtually impossible to obtain lamps having uniform distribution of fill and, therefore, exhibiting uniform ignition time, without resorting to additional work operations. Furthermore, even in the case of lamps having only one type of fill it was frequently difiicult to obtain the desired uniform distribution without resorting to a separate fluffing operation in which the shredded fill was redistributed with the aid of a blast of air.

It is, therefore, an object of this invention to provide a method and apparatus for improving the technique of filling and distributing filamentary materials into containers such as, for example, flashlamp envelopes.

It is a further object of this invention to provide a method and apparatus adapted to fill flashlamp envelopes with filamentary material of various sizes automatically while maintaining uniform distribution.

It is a further object of this invention to provide a method and apparatus for filling focal plane type lamps automatically with two gauges of filamentary material, while maintaining proper distribution in each, avoiding mixing of the two, and placing each in in its proper location.

We have found that some of these objects and other ad- "ice vantages can be obtained in accordince with our invention by shaping the nozzle which delivers the fill into the container to set up eddy currents within the flashlamp.

It has been further found that this feature can be further improved upon so as to accomplish all of the above objects by giving this nozzle a rotary motion.

In the drawings which illustrate preferred embodiments of the apparatus of this invention FIGURE 1 is a side elevation partly in section of the relevant portion of the apparatus showing a tube in which the shredded particles are being carried toward the flashlamp envelope, an air motor and a revolving nozzle feeding the shredded particles into a flashlamp envelope, together with representative parts of the shredding and delivery system.

FIGURE 2 shows a back elevation partly in section of the air motor shown in FIGURE 1.

FIGURE 3 is a side elevation partly in section showing a mechanism of the type illustrated in FIGURE 1 being provided, however, with an electric motor rather than an air motor.

The unique filling nozzle which has been found to give extremely satisfactory results in producing uniformly distributed fill in flashlamp envelopes is illustrated in the drawings at 10. This nozzle is preferably made of a piece of straight brass tubing about Mi-VZ outside diameter. The one end 12 of the nozzle shown is adapted for securing it to a rotary driven hollow shaft of substantially the same inside diameter by means of a coupling collar of a type shown at 14. The other end of the nozzle which feeds the shredded particles into the envelope is formed by bending the tubing through an angle of preferably about 30 and then cutting off the projecting edge of the tubing. This end is, for example, shown at point 15 of the drawing. A nozzle of this type can readily be used in its non-rotating form in the filling of flashlamp envelopes to obtain substantially uniform distribution of the fill in the envelope. If the non-rotating nozzle is inserted to a point within the envelope so that the shredded particles strike the inside of the bulb neck near its juncture with the bulb ous portion of the envelope the shredded particles will rebound into the inside of the bulb itself. This results in far fewer rejects for failure to obtain uniform distribution than would be the case if a straight nozzle were used. Furthermore, it helps to reduce the variability and improves the average quality of fill.

However, when the improved nozzle herein above described is used in conjunction with a spinning mechanism it has been found to further improve the quality of the product produced and has even been found to be adaptable for use in the filling of focal plane type lamps which use two separate fills differing in gauge. In its essentials the improved device consists of a nozzle having a curved delivery end and a spinning device for rotating the nozzle during the period in which the shredded particles are being delivered to the envelope. In the preferred example illustrated in FIGURE 3 of the drawings the nozzle is caused to rotate by means of an electric motor 20 provided with a hollow shaft 22 coupled to the nozzle 10 by means of sleeve 14 and set screws 13. The receiving end of the hollow shaft 22 of the motor is provided with a funnel-like element 24 detachably secured to it by means of set screw 25. The motor and its attached rotating nozzle and funnel is so positioned with respect to the delivery tube 30 in preferred embodiments of this invention that an air gap which may vary from zero to 2" is provided therebetween. The tube 30' leads back to the source of filamentary material which is illustrated in this case as a rotary cutter where the foil used in making fill is shredded. In the illustrated embodiment the air current carrying the particles in tube 30 is developed by means of a venturi assembly 40. However, it is unquestionably true that the rotary nozzle can be used with equal advantage if the suction head providing the air current is positioned at a point beyond the fiashlamp envelope if these elements are adapted for use with the apparatus as shown in Geiger and Davidson Patent Number 2,347,046.

The embodiment illustrated in FIGURE 1 of the drawings differ-s only from that shown in FIGURE 3 in the means for rotating the nozzle. In this case the hollow shaft 50, of which a funnel 5'6 is a part, together with nozzle 58, is driven by an air jet provided by a blast of air supplied through air line '60, valve 62' and nozzle 64. Valve 62 provides means for regulating the amount of air supply and controlling the speed of the rotating shaft 50. The air from nozzle 6'4 is made to impinge on milled slots 57 provided on the outside edge of the funnel 56 as shown in FIGURE 2. The funnel and hollow shaft being set in ball bearings 70 and mounted on a bracket 72 enables the tube to be positioned appropriately with respect to the tubing 74 through which the shredded particles are supplied.

In some cases it has been found desirable to insert the rotary nozzle farther into the bulb than is desirable when the stationary bent nozzle is used. This insures even distribution and keeps all the shredded particles within the bulb.

While operating speeds ranging between 1750 r.p.m. and 4800 r.p.m. have been used successfully it has been found that speeds in the vicinity of 2100 r.p.m. are most desirable if the best all-around results are to be obtained.

The air gap between the funnel and the delivery tube has been found to be essential in those cases in which the venturi means of propelling the shredded particles is used.- It has, for example, been found that if the gap between the funnel and the delivery tube is too small more air reaches the lamp envelope than can be tolerated in the production of flufiy fills. By regulating the air gap any compacting tendency can be avoided. H As has been indicated hereinabove at the preferred speed of approximately 2100 r.p.m. the air gap ranges from zero to approximately 2". This has been found to vary with the pressure of the air within the carrying tube and with the type of fill being made. This air pressure may also vary over rather wide limitations. However, for best results it has been found that air pressures of about 6 to 10 pounds are considered suitable for the even distribution of extremely fine shredded particles, for, example, one part of the charge at the focal plane lamps. lnrother types of lamps the recommended air pressure is closer to 20 pounds, and in a 'few types it may run to 40 pounds.

When the. apparatus of the type shown in the drawings and described in the specification is made use of to fill photoflash lamps the foil 80 from which fill is made as shown in FIGURE 1 is fed into the rotary cutter 82, which cuts off strips or shredded particles which are then picked up in a pickup shoe 84 and sucked into tube 86 by the action of the venturi 88 and pushed through delivery tube 74. The shredded particles are then charged into the revolving funnel 5 6 and passed on down through the hollow shaft 50, and are ultimately discharged from the curbed end of the nozzle 58 within the glass envelope In those cases in which the rotary nozzle is to be used for filling focal plane lamps the rotary cutter is adjusted so as to cut relatively coarse shreds. These are fed into the fiashlamp envelope by means of the rotary nozzle which is placed close to the mouth of the flashlarnp envelope which permits the shredded particles to be evenly distributed in the top half of the fiashlamp envelope. Another rotary cutter is adjusted to cut relatively fine shreds and then feeds the shredded particles into the lamp through another rotary nozzle which has been well inserted into the lamp so that the fine particles are deposited in an evenly distributed fluffy manner near the entrance to the bulb.

In those cases in which the rotary nozzle is to be used in the manufacture of single gauge types of flashlamps a single rotary cutter is adjusted to cut the required size and number of shreds which are then fed into the flashlamp envelope by means of the rotary nozzle inserted well within the lamp. The positioning of the nozzle well within the envelope and off the axis of the neck of the envelope serves to promote a fill mass rotation within the envelope during the fill cycle. A nozzle rotation in the vicinity of 2.100 r.p.m. helps maintain this fill mass rotation, which in turn is an aid in the production of strong well knit fill-s, evenly distributed throughout the bulb area.

While the above description and drawings submitted herewith disclose preferred and practical embodiments of the method and apparatus for introducing filamentary material into flashlight envelopes it will be understood by those skilled in the art that the specific details of construction and arrangement of parts as shown and described are by way of illustration and are not to be con strued as limiting the scope of the invention.

This application is a division of applicants copending application Serial No. 192,224 filed October 26, 1950, issued on December 4, 1956, United States Patent No. 2,772,703.

What we claim is:

The method of filling the innermost portion of a flash lamp with coarse metal shreds and the outer portion with fine shreds, said method comprising: placing a nozzle close to the mouth of a flash lamp envelope and feeding coarse shreds through said nozzle into said envelope and then placing another nozzle farther into the envelope and feeding fine shreds through said other nozzle into the nearer portion of said lamp.

References Cited in the file of this patent UNITED STATES PATENTS 2,722,355 Anderson Nov. 1, 1955 2,759,646 White Aug. 21, 1'95 6 2,772,703 Bennett et a1. Dec. 4, 1956 

